海拔高度对导线负极性直流电晕特性的影响

Effect of Altitude on Negative Polarity DC Corona Characteristics of Conductors

直流线路电晕效应引发的电磁环境问题是线路结构设计和导线选型的关键制约因素,而目前针对海拔高度对负极性直流电晕效应影响的研究,大多未能将放电微观过程和宏观特性相联系,相关机理和规律尚不完善。基于流体动力学理论,文中分析了海拔对电晕放电参数及微观特性的影响;利用小电晕笼和高频电流测量系统,在20~4320m范围内7个不同海拔点进行试验,采集了不同海拔下包括电晕电流脉冲、无线电干扰和可听噪声水平等在内的放电宏观特性参数数据,并获得了考虑海拔影响的电晕效应拟合函数关系。结果表明:海拔升高,电晕电流脉冲幅值和重复频率均增大。电晕电流平均值与导线表面场强的幂函数成正比,比例系数为海拔高度的分段线性函数。无线电干扰和可听噪声也增大,与电晕电流平均值之间呈幂函数关系,且随海拔高度变化而变化。

The electromagnetic environmental problems caused by corona effect of DC line is the key constraint factor for the design of line structure and wire selection.However,most of the current studies on the influence of altitude on the negative DC corona effect have failed to link the micro-processes of the discharge with the macroscopic characteristics,and the relevant mechanisms and laws are still incomplete.Based on the hydrodynamic model,the effects of altitude on the parameters and microscopic characteristics of corona discharge are analyzed.By using a small corona cage and a high frequency current measurement system,tests were conducted at 7 different altitude points in the range of 20 m~4320 m,data on the macroscopic characteristic parameters of the discharge,including corona current pulse,radio interference and audible noise level were collected at different altitudes,and the fitted functional relationship of the corona effect which considers the effect of altitude was obtained.The results show that the amplitude and repetition frequency of corona current pulse increase with altitude.The average corona current is proportional to the power function of the wire surface field strength,and the scale coefficient is a piecewise linear function of altitude.Radio interference and audible noise also increase with the increase of altitude,and they both have a power function relationship with the mean corona current,and change with the altitude.